A new BOD estimation method employing a double-mediator system by ferricyanide and menadione using the eukaryote Saccharomyces cerevisiae

A new biochemical oxygen demand (BOD) sensing method employing a double-mediator (DM) system coupled with ferricyanide and a lipophilic mediator, menadione and the eukaryote Saccharomyces cerevisiae has been developed. In this study, a stirred micro-batch-type microbial sensor with a 560 μL volume and a two-electrode system was used. The chronamperometric response of this sensor had a linear response between 1 μM and 10 mM hexacyanoferrate(II) (r² = 0.9995, 14 points, n = 3, average of relative standard deviation and R.S.D._av = 1.3%). Next, the optimum conditions for BOD estimation by the DM system (BOD_DM) were investigated and the findings revealed that the concentration of ethanol, used to dissolve menadione, influenced the sensor response and a relationship between the sensor output and glucose glutamic acid concentration was obtained over a range of 6.6-220 mg O₂ L⁻¹ (five points, n = 3, R.S.D._av 6.6%) when using a reaction mixture incubated for 15 min. Subsequently, the characterization of this sensor was studied. The sensor responses to 14 pure organic substances were compared with the conventional BOD₅ method and other biosensor methods. Similar results with the BOD biosensor system using Trichosporon cutaneum were obtained. In addition, the influence of chloride ion, artificial seawater and heavy metal ions on the sensor response was investigated. A slight influence of 20.0 g L⁻¹ chloride ion and artificial seawater (18.4 g L⁻¹ Cl⁻) was observed. Thus, the possibility of BOD determination for seawater was suggested in this study. In addition, no influence of the heavy metal ions (1.0 mg L⁻¹ Fe³⁺, Cu²⁺, Mn²⁺, Cr³⁺ and Zn²⁺) was observed. Real sample measurements using both river water and seawater were performed and compared with those obtained from the BOD₅ method. Finally, stable responses were obtained for 14 days when the yeast suspension was stored at 4 °C (response reduction, 93%; R.S.D. for 6 testing days, 9.1%).     

A surface-fluorinated-TiO2-KMnO4 photocatalytic system for determination of chemical oxygen demand

A new method for chemical oxygen demand (COD) determination has been developed, based on photocatalytic oxidative degradation by using a fluorinated-TiO₂-KMnO₄ system. In such a system, a linear correlation is observed between the amount of oxidizable dissolved organic matter and the amount of MnO₄⁻ consumed by the coupled reduction process. Thus, the COD determination is transformed to a simple and direct determination of the deletion of MnO₄⁻. The surface fluorination of TiO₂ nanoparticles can enhance the rate of photocatalytic oxidation of organic matter and the rate of coupled photocatalytic reduction of MnO₄⁻. This makes the method be rapid, environment friendly and easy for operation. Under optimized conditions, this method can respond linearly to COD of potassium hydrogen phthalate (KHP) in the range of 0.1-280 mg L⁻¹, with a detection limit of 0.02 mg L⁻¹ COD. The COD in samples of tap water, lake water and paper industry sewage has been determined satisfactorily by using this method.     

A novel approach based on ferricyanide-mediator immobilized in an ion-exchangeable biosensing film for the determination of biochemical oxygen demand

A novel biochemical oxygen demand (BOD) sensing method employing a ferricyanide (FC) mediator immobilized in an ion-exchangeable polysiloxane was developed. The ion-exchangeable polysiloxane containing alkylammonium groups (PAPS-Cl) was synthesized by sol-gel reaction of 3-(aminopropyl)trimethoxysilane (APTMOS) catalyzed by hydrochloric acid. FC was combined in PAPS-Cl via ion-association and the product was labeled as PAPS-FC, which was employed for a modified glassy carbon electrode. The apparent diffusion coefficient (D_app) of FC on the modified glassy carbon electrode was 9.8 × 10⁻¹¹ cm² s⁻¹. In a three-electrode system, a linear relationship between the anodic current responses and glucose/glutamate (GGA) concentration was obtained up to 40 mg O₂ L⁻¹ (r = 0.994) when the reaction mixture was incubated for 30 min. Single sensor and piece-to-piece reproducibility were less than 3.8 and 7.7%, respectively. The effects of dissolved oxygen, pH, temperature and co-existing substances on the BOD responses were studied. The sensor responses to nine pure organic substances were compared with the conventional BOD₅ method and other biosensor methods. Detection results of seawater samples were compared with those obtained from the BOD₅ method and showed a good correlation (r = 0.988).     

Construction of a novel molecularly imprinted sensor for the determination of O,O-dimethyl-(2,4-dichlorophenoxyacetoxyl)(3′-nitrophenyl)methinephosphonate

A novel voltammetric sensor for O,O-dimethyl-(2,4-dichlorophenoxyacetoxyl)(3′-nitrophenyl)methinephosphonate (Phi-NO₂) based on molecularly imprinted polymer (MIP) film electrode is constructed by using sol-gel technology. The sensor responds linearly to Phi-NO₂ over the concentration range of 2.0 × 10⁻⁵ to 1.0 × 10⁻⁸ mol L⁻¹ and the detection limit is 1.0 × 10⁻⁹ mol L⁻¹ (S/N = 3). This sensor provides an efficient way for eliminating interferences from coexisting substances in the solution. The high sensitivity, selectivity and stability of the sensor demonstrates its practical application for a simple and rapid determination of Phi-NO₂ in cabbage samples.     

Enzyme mimics of spinel-type CoxNi1−xFe2O4 magnetic nanomaterial for eletroctrocatalytic oxidation of hydrogen peroxide

A series of spinel-type Co_xNi_1−xFe₂O₄ (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0) magnetic nanomaterials were solvothermally synthesized as enzyme mimics for the eletroctrocatalytic oxidation of H₂O₂. X-ray diffraction and scanning electron microscope were employed to characterize the composition, structure and morphology of the material. The electrochemical properties of spinel-type Co_xNi_1−xFe₂O₄ with different (Co/Ni) molar ratio toward H₂O₂ oxidation were investigated, and the results demonstrated that Co_0.5Ni_0.5Fe₂O₄ modified carbon paste electrode (Co_0.5Ni_0.5Fe₂O₄/CPE) possessed the best electrocatalytic activity for H₂O₂ oxidation. Under optimum conditions, the calibration curve for H₂O₂ determination on Co_0.5Ni_0.5Fe₂O₄/CPE was linear in a wide range of 1.0 × 10⁻⁸–1.0 × 10⁻³ M with low detection limit of 3.0 × 10⁻⁹ M (S/N = 3). The proposed Co_0.5Ni_0.5Fe₂O₄/CPE was also applied to the determination of H₂O₂ in commercial toothpastes with satisfactory results, indicating that Co_xNi_1−xFe₂O₄ is a promising hydrogen peroxidase mimics for the detection of H₂O₂.     

A new generation of cyanide ion-selective membranes for flow injection application: part II. Comparative study of cyanide flow-injection detectors based on thin electroplated silver chalcogenide membranes

Using induced cathodic electrodeposition a number of silver chalcogenide thin layer membranes of non-trivial composition have been synthesized and their performance as ion-selective flow-injection potentiometric detectors (FIPDs) for free cyanide has been critically estimated in the context of the stringent requirements for toxic cyanide environmental monitoring. AgSCN/Ag₂S, Ag₂S, Ag_2+δSe, Ag_2+δSe_1−xTe_x (0 < δ < 0.25 and x ≈ 0.13), Ag₂Se and Ag₂Se_1−xTe_x electroplated membranes were selected for the present performance-based comparative study in order to obtain a feedback information about the effect of membrane composition. Both silver selenide and Te-doped silver selenide membranes, irrespective of their stoichiometry with respect to silver, exhibit the lowest detection limit for CN⁻ (52 ppb) with linear double-Nernstian response down to 130 ppb. The type of chalcogene anion in the membrane composition proves to exert dominant effect on the general performance characteristics of the newly developed FIPDs. The silver stoichiometry (intrinsic defects factor) and the inclusion of Te-dopant (extrinsic defects factor) have more pronounced effect on the profile of the output signal and exert moderate control on the detectors selectivity and baseline stability. This new generation of CN⁻—ion-selective membranes for FIPDs exhibits high selectivity against the common interferents present in cyanide effluents such as SCN⁻, S₂O₃²⁻, Cl⁻ and do not get poisoned in the presence of S²⁻. Moreover, their long-term stability and signal reproducibility, which make redundant the regular day-to-day calibration, coupled with the cost-effective technology for membranes preparation and easy re-generation make them attractive candidates for incorporation into automated in-field devices for in situ cyanide toxic species monitoring.     

Assessing the effect of oxygen and microbial inhibitors to optimize ferricyanide-mediated BOD assay

Methods for short-term BOD analysis (BOD_st) based on ferricyanide mediator reduction have succeeded in overcoming some problems associated with the standard BOD test analysis (BOD₅) such as long-term incubations (5 days), the need to dilute samples and low reproducibility. Here we present a bioassay where a Klebsiella pneumoniae environmental strain successfully reduces ferricyanide without de-aeration of the samples with linear BOD₅ ranges between 30 and 500 mg L⁻¹ or 30 and 200 mg L⁻¹, using glucose-glutamic acid solution (GGA) or OECD standards respectively. We further propose a new assay termination solution that allows higher reproducibility and standardization of the cell-based assay, employing formaldehyde (22.7 g L⁻¹) or other compounds in order to stop ferricyanide reduction without affecting the amperometric detection and therefore replace the centrifugation step normally used to stop microbial-driven reactions in ferricyanide-mediated bioassays. These improvements led to an accurate determination of real municipal wastewater samples.     

A chemiluminescence biochemical oxygen demand measuring method

A new chemiluminescence biochemical oxygen demand (BOD_CL) determining method was studied by employing redox reaction between quinone and Baker's yeast. The measurement was carried out by utilizing luminol chemiluminescence (CL) reaction catalyzed by ferricyanide with oxidized quinone of menadione, and Saccharomyces cerevisiae using a batch-type luminometer. In this study, dimethyl sulfoxide was used as a solvent for menadione. After optimization of the measuring conditions, the CL response to hydrogen peroxide in the incubation mixture had a linear response between 0.1 and 100 μM H₂O₂ (r² = 0.9999, 8 points, n = 3, average of relative standard deviation; R.S.D._av = 4.22%). Next, a practical relationship between the BOD_CL response and the glucose glutamic acid concentration was obtained over a range of 11-220 mg O₂ L⁻¹ (6 points, n = 3, R.S.D._av 3.71%) with a detection limit of 5.5 mg O₂ L⁻¹ when using a reaction mixture and incubating for only 5 min. Subsequently, the characterization of this method was studied. First, the BOD_CL responses to 16 pure organic substances were examined. Second, the influences of chloride ions, artificial seawater, and heavy metal ions on the BOD_CL response were investigated. Real sample measurements using river water were performed. Finally, BOD_CL responses were obtained for at least 8 days when the S. cerevisiae suspension was stored at 4 °C (response reduction, 69.9%; R.S.D. for 5 testing days, 18.7%). BOD_CL responses after 8 days and 24 days were decreased to 69.9% and 35.8%, respectively, from their original values (R.S.D. for 8 days involving 5 testing days, 18.7%).     

Immobilization of [Cu(bpy)2]Br2 complex onto a glassy carbon electrode modified with α-SiMo12O40 and single walled carbon nanotubes: Application to nanomolar detection of hydrogen peroxide and bromate

A simple procedure has been used for preparation of modified glassy carbon electrode with carbon nanotubes and copper complex. Copper complex [Cu(bpy)₂]Br₂ was immobilized onto glassy carbon (GC) electrode modified with silicomolybdate, α-SiMo₁₂O₄₀⁴⁻ and single walled carbon nanotubes (SWCNTs)_. Copper complex and silicomolybdate irreversibly and strongly adsorbed onto GC electrode modified with CNTs. Electrostatic interactions between polyoxometalates (POMs) anions and Cu-complex, cations mentioned as an effective method for fabrication of three-dimensional structures. The modified electrode shows three reversible redox couples for polyoxometalate and one redox couple for Cu-complex at wide range of pH values. The electrochemical behavior, stability and electron transfer kinetics of the adsorbed redox couples were investigated using cyclic voltammetry. Due to electrostatic interaction, copper complex immobilized onto GC/CNTs/α-SiMo₁₂O₄₀⁴⁻ electrode shows more stable voltammetric response compared to GC/CNTs/Cu-complex modified electrode. In comparison to GC/CNTs/Cu-complex the GC/CNTs/α-SiMo₁₂O₄₀⁴⁻ modified electrodes shows excellent electrocatalytic activity toward reduction H₂O₂ and BrO₃⁻ at more reduced overpotential. The catalytic rate constants for catalytic reduction hydrogen peroxide and bromate were 4.5(±0.2) × 10³ M⁻¹ s⁻¹ and 3.0(±0.10) × 10³ M⁻¹ s⁻¹, respectively. The hydrodynamic amperommetry technique at 0.08 V was used for detection of nanomolar concentration of hydrogen peroxide and bromate. Detection limit, sensitivity and linear concentration range proposed sensor for bromate and hydrogen peroxide detection were 1.1 nM and 6.7 nA nM⁻¹, 10 nM-20 μM, 1 nM, 5.5 nA nM⁻¹ and 10 nM-18 μM, respectively.     

Mineral content and botanical origin of Spanish honeys

Eleven elements (Zn, P, B, Mn, Mg, Cu, Ca, Ba, Sr, Na and K) were determined by inductively plasma coupled spectrometry in 40 honey samples from different places of Spain and four different botanical origins: Eucalyptus (Eucalyptus sp.), Heather (Erica sp.), Orange-blossom (Citrus sinensis) and Rosemary (Rosmarinus officinalis). K, Ca and P show the higher levels with average concentrations ranged between 434.1-1935 mg kg⁻¹ for K; 42.59-341.0 mg kg⁻¹ for Ca and 51.17-154.3 mg kg⁻¹ for P. Levels of Cu (0.531-2.117 mg kg⁻¹), Ba (0.106-1.264 mg kg⁻¹) and Sr (0.257-1.462 mg kg⁻¹) are the lowest in all honey samples. Zn (1.332-7.825 mg kg⁻¹), Mn (0.133-9.471 mg kg⁻¹), Mg (13.26-74.38 mg kg⁻¹) and Na (11.69-218.5 mg kg⁻¹) concentrations were found strongly dependent on the kind of botanical origin.Results were submitted to pattern recognition procedures, unsupervised methods such as cluster and principal components analysis and supervised learning methods like linear discriminant analysis in order to evaluate the existence of data patterns and the possibility of differentiation of Spanish honeys from different botanical origins according to their mineral content. Cluster analysis shows four clusters corresponding to the four botanical origins of honey and PCA explained 71% of the variance with the first two PC variables. The best-grouped honeys were those from heather; eucalyptus honeys formed a more dispersed group and finally orange-blossom and rosemary honeys formed a less distinguishable group.     

Theoretical study of the triplet excited state of PtPOP and the exciplexes M-PtPOP (M = Tl, Ag) in solution and comparison with ultrafast X-ray scattering results

The [Pt₂(H₂P₂O₅)₄]⁴⁻ ions in the ground and excited states and the excited-state complexes M-[Pt₂(H₂P₂O₅)₄]³⁻ and M₂-[Pt₂(H₂P₂O₅)₄]²⁻ (M = Ag, Tl) were studied in solution with various density functional theory (DFT) functionals from Gaussian 09 and Amsterdam Density Functional (ADF) programs. Calculated results were compared with ultrafast X-ray solution scattering data. Time dependent DFT (TD-DFT) calculations with the B3PW91 functional and unrestricted open shell calculations with the mPBE functional produce good agreement with the experimental results. Compared to gas phase calculations, the surrounding solvent is found to play an important role to shorten the Pt-Pt and M-Pt (M = Ag, Tl) bond lengths, lowering the molecular orbital energies and influences the molecular orbital transitions upon excitation, which stabilizes the excited transient molecules in solution.     

Determination of chemical oxygen demand values by a photocatalytic oxidation method using nano-TiO2 film on quartz

A COD measurement by a photocatalytic oxidation method using nano-TiO₂ film was investigated. K₂Cr₂O₇ was added into the solution to enhance the efficiency of photocatalytic degradation, and simultaneously K₂Cr₂O₇ was reduced to Cr(III) by photogenerated electrons, which were adsorbed on the surface of TiO₂. The measuring principle was based on direct determination of Cr(III) concentration which was proportional to the COD value. Under the optimized experiment condition, the application range was 20-500 mg l⁻¹, and the detection limit was 20 mg l⁻¹. The immobilization of photocatalyst on the supports could not only solve the problem of low recovery of the catalyst and hard separation from the solution, but also overcome its shortcoming of poor stability. Applied this method to the determination of real samples, it was found to be rapid and environmentally friendly. Additionally, the method proposed above for determination of COD was in excellent correspondence with values obtained by using the conventional method.     

Theoretical study of the thermochemistry and the kinetics of the SFxCl (x = 0-5) series

A systematic thermodynamic and kinetic study of the entire SF_xCl (x = 0-5) series has been carried out. High-level quantum chemical composite methods have been employed to derive enthalpy of formation values from calculated atomization and isodesmic energies. The resulting values for the SCl, SFCl, SF₂Cl(C₁), SF₃Cl(C_s), SF₄Cl(C_s) and SF₅Cl molecules are 28.0, −36.0, −64.2, −134.3, −158.2 and −237.1 kcal mol⁻¹. A comparison with previous experimental and theoretical values is presented. Statistical adiabatic channel model/classical trajectory, SACM/CT, calculations of selected complex-forming and recombination reactions of F and Cl atoms with radicals of the series have been performed between 200 and 500 K. The reported rate coefficients span over the normal range of about 6 × 10⁻¹² and 5 × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹ expected for this type of barrierless reactions.     

Simple hollow fiber renewal liquid membrane extraction method for pre-concentration of Cd(II) in environmental samples and detection by Flame Atomic Absorption Spectrometry

A hollow fiber renewal liquid membrane (HFRLM) extraction method to determine cadmium (II) in water samples using Flame Atomic Absorption Spectrometry (FAAS) was developed. Ammonium O,O-diethyl dithiophosphate (DDTP) was used to complex cadmium (II) in an acid medium to obtain a neutral hydrophobic complex (ML₂). The organic solvent introduced to the sample extracts this complex from the aqueous solution and carries it over the poly(dimethylsiloxane) (PDMS) membrane, that had their walls previously filled with the same organic solvent. The organic solvent is solubilized inside the PDMS membrane, leading to a homogeneous phase. The complex strips the lumen of the membrane where, at higher pH, the complex Cd-DDTP is broken down and cadmium (II) is released into the stripping phase. EDTA was used to complex the cadmium (II), helping to trap the analyte in the stripping phase. A multivariate procedure was used to optimize the studied variables. The optimized variables were: sample (donor phase) pH 3.25, DDTP concentration 0.05% (m/v), stripping (acceptor phase) pH 8.75, EDTA concentration 1.5 × 10⁻² mol L⁻¹, extraction temperature 40 °C, extraction time 40 min, a solvent mixture N-butyl acetate and hexane (60/40%, v/v) with a volume of 100 μL, and addition of ammonium sulfate to saturate the sample. The sample volume used was 20 mL and the stripping volume was 165 μL. The analyte enrichment factor was 120, limit of detection (LOD) 1.3 μg L⁻¹, relative standard deviation (RSD) 5.5% and the working linear range 2-30 μg L⁻¹.     

Study on photocatalytic oxidation for determination of the low chemical oxygen demand using a nano-TiO2-Ce(SO4)2 coexisted system

A new photocatalytic system, nano-TiO₂-Ce(SO₄)₂ coexisted system, which can be used to determine the low chemical oxygen demand (COD) is described. Nano-TiO₂ powders is used as photocatalyst in this system. The measuring method is based on direct determination of the concentration change of Ce(IV) resulting from photocatalytic oxidation of organic compounds. The mechanism of the photocatalytic oxidation for COD determination was discussed and the optimum experimental conditions were investigated. Under the optimum conditions, a good calibration graph for COD values between 1.0 and 12 mg l⁻¹ was obtained and the LOD value was achieved as low as 0.4 mg l⁻¹. When determining the real samples, the results were in good agreement with those from the conventional methods.     

Bilayer lipid membrane biosensor with enhanced stability for amperometric determination of hydrogen peroxide

In this paper, a polydopamine (PDA) film is electropolymerized on the surface of bilayer lipid membrane (BLM) which is immobilized with horseradish peroxidase (HRP). The coverage of the PDA film on HRP/BLM electrode is monitored by electrochemical impedance spectroscopy (EIS). The electrocatalytic reduction of H₂O₂ at the PDA/HRP/BLM electrode is studied by means of cyclic voltammetry (CV). The biosensor has a fast response to H₂O₂ of less than 5 s and an excellent linear relationship is obtained in the concentration range from 2.5 × 10⁻⁷ to 3.1 × 10⁻³ mol L⁻¹, with a detection limit of 1.0 × 10⁻⁷ mol L⁻¹ (S/N = 3). The response current of BLM/HRP/PDA biosensor retains 84% of its original response after being stored in 0.1 mol L⁻¹ pH 7.0 PBS at 4 °C for 3 weeks. The selectivity, repeatability, and storage stability of PDA/HRP/BLM biosensor are greatly enhanced by the coverage of polydopamine film on BLM.     

Electrochemical behavior of hexafluoroniobate, heptafluorotungstate, and oxotetrafluorovanadate anions in N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide room temperature ionic liquid

Electrochemical behavior of hexafluoroniobate (Nb(V)F₆⁻), heptafluorotungstate (W(VI)F₇⁻), and oxotetrafluorovanadate (V(V)OF₄⁻) anions has been investigated in N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPyrTFSA) ionic liquid at 298 K by means of cyclic voltammetry and chronoamperometry. Cyclic voltammograms at a Pt electrode showed that Nb(V)F₆⁻ anion is reduced to Nb(IV)F₆²⁻ by a one-electron reversible reaction. Electrochemical reductions of W(VI)F₇⁻ and V(V)OF₄⁻ anions at a Pt electrode are quasi-reversible and irreversible reactions, respectively, according to cyclic voltammetry. The diffusion coefficients of Nb(V)F₆⁻, W(VI)F₇⁻ and V(V)OF₄⁻ determined by chronoamperometry are 1.34 × 10⁻⁷, 7.45 × 10⁻⁸ and 2.49 × 10⁻⁷ cm² s⁻¹, respectively. The Stokes radii of Nb(V)F₆⁻, W(VI)F₇⁻, and V(V)OF₄⁻ in BMPyrTFSA have been calculated to be 0.23, 0.38, and 0.12 nm, from the diffusion coefficients and viscosities obtained.     

Critical parameters for isobutane determined by the image analysis

(p, ρ, T) Measurements and visual observations of the meniscus for isobutane were carried out carefully in the critical region over the range of temperatures: −15 mK ? (T − T_c) ? 35 mK, and of densities: −7.5 kg · m⁻³ ? (ρ − ρ_c) ? 7.5 kg · m⁻³ by a metal-bellows volumometer with an optical cell. Vapor pressures were also measured at T = (310, 405, 406, 407, and 407.5) K. The critical point of T_c and ρ_c was determined by the image analysis of the critical opalescence which is proposed in this study. The critical pressure p_c was determined to be the pressure measurement at the critical point. Comparisons of the critical parameters with values given in the literature are presented.     

Application of manganese (II) phthalocyanine synthesized in situ in the SiO2/SnO2 mixed oxide matrix for determination of dissolved oxygen by electrochemical techniques

This work describes the in situ immobilization of Mn(II) phthalocyanine (MnPc) in a porous SiO₂/SnO₂ mixed oxide matrix obtained by the sol gel processing method. The chemically modified matrix SiO₂/SnO₂/MnPc, possessing an estimated amount of 8 × 10⁻¹⁰ mol cm⁻² of MnPc on the surface, was used to prepare an electrode to analyze dissolved oxygen in water by an electrochemical technique. The electrode was prepared by mixing the material with ultrapure graphite and evaluated using differential pulse voltammetry. Dissolved O₂ was reduced at −0.31 V with a limit of detection (LOD) equal to 7.0 × 10⁻⁴ mmol L⁻¹. A mechanism involving four electrons in O₂ reduction was determined by the rotating disk electrode technique.     

Design of single chain magnets through cyanide-bearing six-coordinate complexes

The design and preparation of stable cyanide-bearing six-coordinate complexes of formula [M^III(L)(CN)_x]^{(x + l − m)−} (M = trivalent transition metal ion and L = polydentate blocking ligand) are summarized here. Their use as ligands towards either fully hydrated metal ions or coordinatively unsaturated preformed species, to afford a wide variety of low-dimensional metal assemblies whose nuclearity, dimensionality and magnetic properties can be tuned, is also reviewed. Special emphasis is put on the appropriate choice of the end-cap ligand L whose denticity determines the number of coordinated cyanide groups in the mononuclear precursors. Among the different new spin topologies obtained through this rational synthetic strategy, ferromagnetically coupled 4,2-ribbon like bimetallic chains which exhibit slow magnetic relaxation and hysteresis effects (chain as magnets) are one of the most appealing and constitute the heart of the present contribution.